Should have, could have, would have: past modals with real examples
The difference between should have, could have and would have, plus must have and might have for guesses, with real clips of native speakers and how people actually say them.
Chief Language Pedagogy Geek @ Reelang
Should have, could have and would have all talk about the past, and all three talk about a past that didn't happen. The difference is the attitude:
| Form | What it means | Example |
|---|---|---|
| should have + past participle | It was the right thing to do, and it didn't happen (regret or criticism) | I should have called you. |
| could have + past participle | It was possible, and it didn't happen | I could have called you, but I was tired. |
| would have + past participle | It was the result of a different past (imagined) | I would have called you if I'd had your number. |
So "should have" judges the past, "could have" lists the options you had, and "would have" imagines what a different past would have looked like. In speech, all three shrink to should've, could've and would've, and they sound almost like "shoulda", "coulda" and "woulda".
The same pattern (modal + have + past participle) also does a second job: guessing about the past. "She must have left" means you're almost sure. "She might have left" means maybe. "She can't have left" means you're sure she didn't.
Below, each form gets a short explanation and real clips of native speakers using it. After the rules, there's a section on how people actually say these things, which is not always how the grammar books write them. Tap any word in the subtitles to see what it means.
The pattern: modal + have + past participle
Every form in this article is built the same way:
should / could / would / must / might / may / can't + have + past participle
- I should have gone.
- She could have won.
- They would have seen it.
- He must have forgotten.
Three things trip learners up:
- "Have" never changes. It's "she should have", never "she should has". After a modal, the verb stays in its base form, and "have" is that base form.
- The third word is the past participle, not the simple past. "I should have gone", not "I should have went". (Native speakers break this one a lot. More on that later.)
- The negative goes on the modal: shouldn't have, couldn't have, wouldn't have. "I should have not gone" exists, but it's rare and sounds stiff.
Should have: regret and criticism
Use should have for something that was the right thing to do, but didn't happen. When you say it about yourself, it's regret. When you say it about someone else, it's criticism.
In this thrift haul, a creator remembers something she tried on and didn't buy. Listen for "should have just switched out the buttons":
It's the classic shopping regret. The fix was easy, she didn't think of it, and now it's gone.
Here is a shorter one from a different thrift haul. Listen to how quick "should've" is. It's one beat: "SHUD-uv".
Point should have at another person and it becomes a complaint. "You should've told me" is one of the most common lines in TV drama:
The negative, shouldn't have, criticizes something that did happen. In this scene, a daughter says what she thinks of her father leaving:
You'll also hear "I should have known", which means "the signs were there, and I missed them". People say it after a trick, a scam, or a friend who did exactly what they always do.
Could have: the options you didn't take
Use could have for something that was possible in the past, but didn't happen. There's no judgment in it. It just says the door was open.
A very common use is "things could have been worse". After a storm, a reporter stands with a family next to the tree that fell on their house:
Everyone was safe, but it was close. "Could have been much different" is the polite, careful way to say "we could have died".
Could have also describes a choice you had and didn't make: "I could have taken the train, but I wanted to drive."
Could have as a soft complaint
Could have aimed at someone else works like a softer should have. "You could have called" means "calling was possible, so why didn't you?" Add "at least" and the complaint gets sharper:
Couldn't have asked for a better...
The negative, couldn't have, says something was impossible. One phrase with it is everywhere in English: "I couldn't have asked for a better...". It means "this was perfect". Nothing better was possible, so there was nothing better to ask for.
You'll hear it in wedding speeches, award speeches, and travel vlogs. "Couldn't have asked for better weather" is the classic one.
Would have: the past that didn't happen
Use would have to imagine a different past and its result. Most of the time it comes with an if-clause, and the if-clause uses the past perfect (had + past participle). This is the third conditional:
If + had + past participle, ... would have + past participle
- If I had known, I would have come.
- If she'd asked me, I would have helped.
Here it is in a short sketch, in textbook form. Listen for "If I'd known... I would have bought":
"I'd known" is "I had known". In speech, had shrinks to 'd, and would have shrinks to would've, so the whole sentence can come out as "If I'd known, I would've...". Both 'd and 've are small, so listen hard for them.
Would have without "if"
Often the if-clause is just understood. "I would have loved to live in the 1950s" means "if I'd been born then, I would have loved it":
And here's a fun one. "15 year old me would've..." is a common way to talk about your younger self. The if-clause is hidden in "15 year old me": if I had found this bag when I was 15.
"I never would've thought..." is another everyday phrase without an if. It means "I didn't expect this at all".
Must have, might have, can't have: guessing about the past
The same pattern has a second job. It lets you make a guess about the past, based on what you can see now. How sure you are decides the modal:
| How sure | Form | Example |
|---|---|---|
| Almost sure it happened | must have | She must have left. Her coat is gone. |
| Maybe it happened | might have / may have / could have | She might have left early. |
| Almost sure it didn't happen | can't have / couldn't have | She can't have left. Her coat is still here. |
Must have: I'm almost sure
Must have is a conclusion. You see the evidence, and you work out what must have happened. A food vlogger eats very tender chicken and works out how it was cooked:
Must have also has a kind use. "That must have been hard" shows someone you understand what they went through. You can't know exactly how they felt, but you're guessing, and the guess is a form of sympathy:
If you only learn one past modal for conversations, learn this one. "That must have been scary", "that must have been so exciting", "you must have been exhausted" all work as replies when a friend tells you a story.
Might have and may have: maybe
Might have and may have mean the same thing: it's possible this happened. Might is a little more common in speech. This video lists theories about where the word "quiz" comes from. Nobody knows for sure, so every theory gets might have:
May have has a funny side use. People say "I may have..." about a mistake they definitely made. It's a joke: the speaker pretends to be unsure. "I may have eaten all the cookies" means "I ate all the cookies". "I may have underestimated how cheesy that rice was" (a real line from a cooking video) means the rice turned out far too cheesy.
Can't have and couldn't have: it's impossible
Can't have and couldn't have say you're sure something didn't happen, or wasn't true. "It couldn't have been easy for her" means "I'm sure it was hard":
Watch out: you can't use "mustn't have" for this in American English. The opposite of "must have" is "can't have" or "couldn't have". (Some British speakers do say "mustn't have", but it's not the standard form.)
Couldn't have also works with comparatives, to say something was the best or worst possible. "It couldn't have been worse" means it was a disaster. "She couldn't have been nicer" means she was very nice.
How should've, could've and would've sound
In writing, you'll see should have and should've. In speech, the have almost always shrinks. The h disappears and the vowel becomes the weak "uh" sound, so:
- should have → should've → "SHUD-uv"
- could have → could've → "KUD-uv"
- would have → would've → "WUD-uv"
- must have → must've → "MUST-uv"
- might have → might've → "MITE-uv"
In fast, casual speech the v often falls away too, and you get "shoulda", "coulda", "woulda". That's the sound you'll hear most often from native speakers. Say the full "should have" with a clear h, and it sounds careful or emphatic, as in "You really should HAVE told me".
Subtitles almost always write the standard spelling, should have or should've, even when the speaker clearly says "shoulda". So when you watch with subtitles, expect the words on screen to be longer than the sounds you hear.
How native speakers actually say it
The rules above are what you need for writing and exams. Everyday speech moves away from them in a few predictable places. None of these are rare, and all of them come from native speakers. Here's what you'll hear, who says it, and whether to copy it.
Should of, could of, would of
Because should've sounds exactly like "should of", many native speakers write it that way: "I should of known", "you could of told me". It's one of the most common spelling mistakes in English, and you'll see it in comments, texts and social media all the time.
In speech, there's no difference at all. Nobody can hear whether you meant "should've" or "should of". In writing, "should of" is always a mistake. The word is have, because the grammar needs a verb there. So understand it when you see it, but never write it, not even in a quick text if you want your English to look careful. (You won't find it in our subtitles, because they spell it should've or should have.)
Shoulda, coulda, woulda
Shoulda, coulda and woulda are the spoken forms written down. You'll see them in song lyrics, comics, texts, and in the saying "shoulda, coulda, woulda", which means "stop talking about what you didn't do". Our subtitles usually write these as should've and could've, but sometimes they keep the sound:
That's a sketch about what couples would say if they were honest, and both forms come in one line. Here's woulda from a mom explaining her Thanksgiving casserole:
Should you copy it? Saying it, yes: it's simply how fast English sounds. Writing it, only in very casual messages.
"If I would have known" instead of "if I had known"
The textbook third conditional puts had in the if-clause: "If I had known, I would have come." In American English, especially in speech, many people put would have in both halves: "If I would have known, I would have come."
You'll hear it from vloggers, news reporters and movie stars. Here's Timothée Chalamet in his Golden Globes speech, joking that he's thanking Kevin O'Leary from Shark Tank:
"If you would have told me" is the American spoken version of "if you had told me". And here a vlogger explains why these Halloween Oreos would have meant so much to her as a kid:
Grammar books call this a mistake, and in exams and formal writing it is one. But it's so common in the US that you should expect to hear it, and many Americans don't notice it at all. British speakers say it much less. Our advice: understand it, don't write it, and use "if I had" or "if I'd" when you speak too. That works everywhere.
"I could've went" instead of "I could have gone"
Remember the third word: the past participle. With irregular verbs, many native speakers use the simple past instead: "should have went", "could've took", "would've saw". It's common in casual speech in the US, especially in the South and in African American English, and you'll hear it in the UK too.
This news story is about a botched football kick that led doctors to find a tumor. Listen to the line right after the reporter:
The standard form is "it could have gone so much worse". You'll hear the same thing with other verbs: "nobody would've saw me" (seen), "you should've took his advice" (taken), "she could've came" (come). These speakers sound completely natural, and everyone understands them. In an exam, in a job application, or in any writing, use the participle: gone, taken, seen, come, done.
Might could: two modals at once
In the American South, and in some areas north and west of it, people stack two modals: "I might could help you", which means "I might be able to help you". Linguists call it a double modal. It's regional and informal, and you rarely hear it on national TV. On local TV it slips through. Here's a weather forecaster in Omaha, Nebraska, talking about the next few days:
"Might could dry out" means "it might be able to dry out", or just "it might dry out". Don't copy this one unless you live in the South. But if you visit Texas or Alabama and someone says "we might could go tomorrow", now you know what they mean.
Must've for every guess
In conversation, must've does a lot of work. Native speakers use it for almost any confident guess about the past, often without giving any evidence: "She must've known", "he must've forgotten", "I must've left it in the car". It's standard English, and you should copy it.
The one thing to notice: in speech it's almost never "must have" with a clear h. It's "MUST-uv", sometimes just "musta".
Questions and answers
What is the difference between should have, could have and would have?
All three talk about a past that didn't happen. Should have means it was the right thing to do (I should have called), could have means it was possible (I could have called, but I was tired), and would have describes the result of a different past (I would have called if I'd had your number).
Is it correct to say should of?
No. In writing, the correct form is should have or should've. People write should of because should've sounds exactly like it in speech, but the grammar needs the verb have.
Is "if I would have known" correct?
In standard English, the correct form is "if I had known" or "if I'd known". "If I would have known" is very common in American speech, but it counts as a mistake in exams and formal writing.
What does must have been mean?
Must have been is a confident guess about the past, based on evidence. "It must have been cold" means you're almost sure it was cold. "That must have been hard" is also a kind way to show someone you understand what they went through.
What is the difference between must have and might have?
Must have means you're almost sure something happened. Might have means it's possible but you're not sure. The opposite of must have is can't have or couldn't have, not mustn't have.
Is it should have gone or should have went?
Should have gone is correct, because the verb after have is the past participle. Many native speakers say should have went in casual speech, but use gone in writing and exams.
How do you pronounce should've, could've and would've?
The have shrinks to a weak "uv" sound, so should've sounds like "SHUD-uv". In fast speech the v often disappears too, which gives the sounds shoulda, coulda and woulda.
How to get used to past modals
Grammar tables help you build these forms. Understanding them at full speed is a different skill. "Shoulda", "musta" and "I'd known" go by in half a second, and you only catch them after you've heard them many times in real speech. That's what Reelang is for: short videos of native speakers, with subtitles you can tap, at your level.
Start with English videos at your level, or open the app and let the feed pick for you. Every time a speaker says should've, could've or must've, try to hear the 've.